Need advice fixing PEX install

My contractor installed PEX tubing in my basement for the supply and return lines connected to my Burnham boiler. The install was done in the late spring, so I guess he didn't expect the tubing to expand so much once the heat kicked on. Right now, I have two really bad sagging spots. One is about an 8' stretch where the low point is about 1' from the bottom of the joist. The other is also about 8' long with the low point about 18" from the bottom of the joist. There are also a few curves that I plan on straightening out and inserting 90 degree elbows.

So my questions:

1. How do I know how much I can safely cut from the sagging PEX before I reattach to the joists? Do I just wait for the summer to see if the tubing contracts and then bring the tubing up with a few inches of slack?

2. Is adding a right angle or two to each line bad idea or is it highly preferred to have continuous tubing?

Pex manufacturers require support every 32". It sounds like you don't have much support. As with every piping install the more joints you have the more leaks you may get. I'd try to keep the tubing as intact as possible keeping in mind that pex shouldn't be ran stick straight or tied down hard. Because of the expansion contraction the pex pipe should be supported well but allowed to have some movement, sagging is common but if it's well supported it shouldn't be a problem.

The installer did use the mickey mouse ears to hold up the PEX on every other joist, so that is approximately every 32". The problem is that there was too much PEX after it expanded with the heat on and the mickey mouse ears snapped off. Is there are stronger/more appropriate hanger for PEX? For my own peace of mind, I would prefer not to cut and reconnect the PEX.